In the technical field of circuit design, phase interpolators (PI) are widely used in integrated circuits because of high precision and phase controllability of their output clock signals. With the increase of the speed of the mixed signal circuit, the requirement for the precision of a PI circuit is continuously increased. Generally, in a PI, the influences of process variation, parasitic capacitance and parasitic resistance on the circuit cannot be neglected, which often result in phase deviation of the output signal, and thus affect the PI precision.
In conventional technology, PI calibration usually depends on an off-chip component. In small batch of process verification test or mass use, a PI cannot perform self-calibration. The precision loss caused by the change of process, current and temperature cannot be compensated, which affects the accuracy of the output clock signal of the PI.